Low loss cable



0t.'15, 1940. n LDORIAN 2,218,085

LOW LOSS CABLE Filed Aug` 12, 1938 |N vENToR Luc/en Borian ATTORNEYS Patented Oct. 15, 1940 azlaoss Low Loss CABLE Lucien Dorian, New York, N. Y., assignor to Prosper E. Cholet, New Brunswick, N. J. 1

Application August 12, 1938, Serial No. 224,435

ICIaim.

This invention relates to improvements in low loss cables and has for a main object the provision of a cable formed of a plurality of conductors contacting each other at points and spaced apart from each other between said points, there being less surface area of conductors in contact at said points than the surfaces out of contact with each other between said points.

Another object of the invention is the provision of a conductor somewhat of the LiZ type. comprised of a plurality of insulated conductors assembled into a cable with portions oi' their areas in contact and portions of their areas in noncontact relation with the other conductors, the areas of said non-contacting portions being far in excess of the areas of the portions in contact.

A further object of the invention is the provision of a cable formed of a plurality of conductors of sinusoidal form assembled to make point contacts with each other between the nodes of said sines, all other surfaces including said nodes being free to be contacted by surrounding air or any other medium.

A further object of the invention is the provision of a cable formed of four or more conductors each having a series of sinusoidal curves formed therein, said conductors touching each other at point contacts between the nodal points of said curves, thereby leaving a greater portion of said conductors free of contact with anything but the surrounding air.

Other objects will be apparent to those skilled in the art. v

In connection with radio and high frequencies such as encountered in short waves and television transmission and/or reception, the amount of radiation or pick-up depends upon the type of conductor used as an antenna. Likewise in coils or solenolds used in connection with radio or television, the eiiiciency of the coils depends to a great extent upon the type of conductor of which the coil is made.

In the prior art the Litz" type of cable was found to be very eiiicient. This type of cable consists of a plurality of insulated wires (usually insulated with enamel) twisted together and covered with a suitable braid. Coils formed oi' Litz cable at present are considered very eiilcient in the art especially if wound without forms lwhich further reduces the losses. This is particularly true as the higher frequencies are encountered.

This efficiency is believed to be due to the fact that the individual conductors forming the Litz cable are, after the conductors have been twisted together to form the cable, in contact with each other along a line of contact.

According to the present invention, the conductors forming the cable (and in the embodiment herein shown and described I employ four conductors to form a cable) are sinusoidal in form lengthwise, and the sines formed in the cable are put together in interspersed relation so that they contact each other only at point contacts which fall between the nodes of the sine curves, the lo point contacts serving to support the conductors relative to each other and to hold them in such relation that all of the surface areas oi' the conductors outside of these point contacts arev free to be contacted by the air or any other iluid medium surrounding the cable only.

Since the contact between conductors forming the new and improved conductor occurs at points spaced apart from each other instead of along a continuous line as is the case with the Litz cable, the capacityvbetween the conductors is substantially lower than that of conductors in the Litz" cables, this new and improved cable is more particularly adapted to Vhandle radio frequencies with the losses greatly reduced.

Referring now to the drawing- Figure 1 is an enlarged view of a portion of the length of a four conductor cable illustrating one form of the invention;

Figure 2 is a view of a section of a cable, each conductor of which is somewhat modified from that of the forms shown in Figure 1;

Figure 3 is a cross sectional view taken along the line 3 3 of Figure 1 and showing point contacts between the conductors forming the cable; and

Figure 4 is a sectional view taken along the line 4 4 of Figure 1, showing at least one of the conductors at the greatest point of spaced relation between the conductors.

The cable shown in Figure 1 is comprised of conductors 20, 2|, 22 and 2,3. Each of these conductors is formed throughout its length in the form of a sine curve. For example, the sine curve oi' the cable 2l has nodes 20, 20", 20, 20", 20 and 20. 'I'he other cables 2|, 22 and 23 have exactly the same form and the cables are put together in interspersed relation so that they contact each other only at point contacts which fall between the nodes of the sine curves. For example, in Figure 3, which is a sectional view taken along the line 3 3 of Figure 1, it will be noted that the conductor 20 contacts the conductor 22 at a point contact designated by the numeral 24, while conductor 2i contacts the conductor 22 at a point indicated by the numeral 25, and also contacts the conductor 23 at a point indicated by the numeral 26. It will also be noted that the conductors 22 and 23, in addition to being conducted by the conductor 2| at the points indicated, are also in contact with each other at the point 21.

Now, considering the cable shown in Figure 1, at a point where the conductors are spaced apart from each other, for example along the line 4-4 of Figure l as illustrated in Figure 4, the conductor 20 at this point is substantiallyspaced apart from the conductor 22, it is lesser spaced apartfrom the conductor 23 at this point, and the conductor 2i is still nearer to the conductor 20 but yet substantially spaced apart therefrom. Between the line 4-4, which is taken along a maximum nodal point of the curve formed in the conductor 22 and the next adjacent points where the conductors contact each other, which are in the neighborhood of the point 28 of Figure 1, the conductors approach each other and finally make point contacts with each other in the neighborhood of the point 28. Continuing past the point 28, the next nodal points of the conductors define another area in which the conductors are substantially spaced apart, and so on throughout the length of the cable. 'I'he contact between the cables is always a point contact, and these point contacts are spaced apart from each other in accordance with the amplitude of the sine waves formed in the conductors and in accordance with the size of the conductors themselves.

If the points of contact are eliminated, the conductors would not be supported in the proper relation to each other and the cable would therefore be deformable, and thereby the capacity between the conductors forming the cable would be variable.

In the embodiment shown in Figure 2, conductors 30, 3|, 32, and 33 are employed. The curves formed in the conductors, while not pure sine curves, are more or less sinusoidal and, therefore. the conductors can be put together in an interspersed relation so that they only contact each other at point contacts which fall between the peaks of the curves. These point contacts support the conductors and maintain them in fixed relation to each other, the relation being such that all of the surface areas of the conductors, except at these point contacts, are in free communication with the air or the fluid medium surrounding the cable.

'I'he new and improved cable is not only particularly adaptable to currents of such frequencies that they travel along the surface or skin of the conductors, but is also adaptable to transmitting heavy currents in view of the fact that the greater portion of the surface area of the conductors is in free contact with the air and, therefore, heat losses of transmission of such heavy currents are readily radiated into the air, thereby preventing the conductors from heating up to a high temperature, unduly increasing their resistance and thereby preventing greater losses.

Although two embodiments of the invention are herein shown and illustrated. it must be understood that I am not limited to having conductors of sinusoidal form, as it is obvious that the conductors may be of any form so long as they may be put together in interspersed relation having contact with each other only at point contacts which fall between the points at which the conductors are spaced apart from each other.

What is claimed is:

A cable for high frequency currents comprised of a plurality of insulated conductors each of which is formed in a continuous sine curve pattern throughout its length, all said conductors being assembled in interspersed relation, whereby they support each other at point contacts substantially spaced apart from each other along the length of said cable, each conductor being spaced apart from all the others except at said points of contact, thereby providing small capacitance between the conductors where they contact each other, and a capacitance between the surface areas lying between said points smaller than the capacitance between the conductors at the points where they contact each other.

LUCIEN DORIAN. 

